Fixed Eyepiece Telescopes
Larger amateur telescopes often require observers to use ladders and awkward viewing positions
to see objects over much of the sky. These difficulties have been minimized by the development
of ingenious telescopes in which, not only is the eyepiece fixed (or nearly so), but often the
observer can sit or stand in an enclosed space. This room also eliminates insects and can be
heated in winter. A drawback to many of these designs is the need for an accurately polished
flat mirror at least as large as the telescope aperture.
In 1970 I built a 20-inch f/5 telescope driven on a split-ring equatorial mount and housed in a
16-foot dome. After moving to California in 1986, we acquired property in the Tehachapi
Mountains at 6500 feet. I decided to re-erect the telescope. In this design the 20-inch
instrument is inclined at a 35° angle looking down the polar axis into a 20 x 30 inch flat
mirror. The mirrors are pointed by motors that move in response to signals from a small astro
computer, so that the desired area of the sky is reflected up into the telescope. The
image is examined by an observer seated at a desk in an 8 x 10 foot building. More
pictures of this instrument and details on its design and construction are given in my
article on in the June 1995 issue of “Sky and Telescope” magazine, pages 81-84.
